CRI (Denmark) sells a toolset based on the RAISE Specification Language
(RSL) which may be of interest to you. I am not a CRI salesman so you'd
better address to them directly for more information.

The RSL toolset may not be able to generate an interpreter from the
denotational semantics but it enables the programmer to specify the
language's semantics (algebraically and/or denotationally). It has other
interesting features (non-determinism enabled, concurrency). Yielding an
interpreter is IMO just a case of adding a generic piece of RSL code to
the denotational specs.